The suspensions of samples were filtered through Whatman GF/A glass fibre filter paper before reading the colour. Hydrolysis to d-glucose was completed by incubation at 40 °C for 60 min with a mixture of highly purified exo-1,3-β-glucanase (20 U/ml) and β-glucosidase (4 U/ml). Finally, 3 ml of glucose oxidase/peroxidase mixture were added to each suspension and the mixture was incubated at 40 °C for 20 min.